What Are the Causes of Torque Converter Stall?
3 Answers
When the output speed of the torque converter is 0, the corresponding input speed of the torque converter is the stall speed. Function of the Torque Converter: A hydraulic component consisting of a pump impeller, turbine, and stator. It is installed between the engine and transmission, using hydraulic fluid (ATF) as the working medium to transmit torque, convert torque, change speed, and act as a clutch. Classification of Torque Converters: The fluid flow is divided into vortex flow and circular flow. The direction of vortex flow is from the pump impeller to the turbine, then to the stator, and finally back to the pump impeller, forming a continuous cycle. The direction of circular flow is the movement of the fluid along with the working wheel around the axis in a circular motion. The actual direction of the fluid flow is the spiral direction formed by the combination of circular flow and vortex flow.
After driving an automatic transmission car for so many years, torque converter stall is mainly due to issues with the hydraulic transmission fluid. If the fluid level is too low or the oil has deteriorated and become too thick, the transmission efficiency drops directly; if the oil is too thin, it can easily leak, leading to insufficient internal pressure. Another common reason is wear or breakage of the internal blades in the torque converter, preventing the pump and turbine from working efficiently. A faulty lock-up clutch, such as malfunctioning engagement points or sticking, can cause abnormal RPM rise and stalling. Control system failures, like sensor misreporting, may also trigger it. For handling, regularly check the fluid level and color, change the oil every 20,000 kilometers, and pay attention to sluggish acceleration or unusual noises while driving, then promptly visit a shop for inspection and repair.
Once when I accelerated, my car suddenly felt sluggish, and it turned out to be torque converter stall. The reasons are usually insufficient or oxidized/dirty hydraulic fluid failing to lubricate transmission components properly; malfunctioning lock-up clutch control, such as short circuits or misoperations in the electronic control system; or internal wear and aging causing gaps and oil leaks. Nowadays, with smarter cars, the fault code light will alert you. For maintenance, don't skimp on transmission fluid checks—topping up or replacing the fluid can prevent most issues. Maintain smooth driving and avoid sudden acceleration or overheating.
